leaking sight tube Tank Master Valve

[joni os]

Installed Atkins Tank Master 7 months ago. Client reports leak from poly tube. Only noticeable because level rises when pin pulled out and oil use minimal,(Property empty). Loss about 12mm per fortnight.
When installed poly slid on nipple without heat. Thought of cutting poly off nipple and refix with smear of Stag but unsure long term effect Poly/Stag. Have used jubilee clip as temp fix but note Atkins neither supply or recommend hose clip for this purpose.
Comments please.

 

[Best]

Are you completely sure the oil leak is coming from the bottom of the tube?
Very hard to trace oil weeps, as you know, because the kerosine spreads. I have always found the leak to be from the factory joint on standard oil sight gauges where the threaded end of the nipple screws in. The factory seem to use a glue like sealant. I just screw them out and clean the fine threads and use some ptfe tape on it.

 

[joni os]

Thanks for useful comment. Spares site shows tube nipple with o ring seal and I assumed this would be standard, but revist to Atkins site instructs ptfe seal to thread as per your recommendation. I will follow your advise.